| 摘要 |
A tool comprises essentially a head (25) provided with a slot (37) in which is fixed a drive lug (23) with two pins (35). The latter (35) have cutting edges (33) for making a hole (17). When the tool is rotated, the screw (13) is driven into the material (15), while the cutting edges (33) cut out the hole (17) during several rotations of the tool. While the hole (17) is being cut, the head (19) of the screw moves along the pins (35) at a speed in excess of that of the cutting edges (33). Because of the relatively small advance of the cutting edges (33), the cutting depth of the hole is small and a clean hole is achieved in which the head (19) of the screw is embedded. |
